Hamid Karzai, the president of Afghanistan, has condemned the film that sparked violence in Libya and Egypt as an abhorrence and insult to all Muslims, warning that it would damage inter-faith relations.

The strongly worded statement is likely to be the first many Afghans hear of the once obscure, 13-minute film, which was made by a California property developer and attacks the prophet Muhammad, suggesting he was a fraud. The low-budget film, appearing like a trailer, was first shown on YouTube, then on Egyptian television.

Karzai called for "efforts to prevent the release of this insulting film", but did not call for restraint in demonstrations, or criticise the rioting, or the death of the US ambassador in Libya.

Instead he said the production would fan tension, and called for the film to be banned. "This offensive act has stoked inter-faith enmity and confrontation and badly impacted the peaceful coexistence between human beings," the English-language statement said.

Clerics warned that the film was likely to kindle anger among devout Afghans, with a real possibility of more violence.

Said Hosain Alami Balkhi, an influential MP and cleric, said: "I am sure in the future when the nation and society understand about the film, that this is an insult to Islam, there will be a very serious reaction, as there was before when the Qur'ans were burned [by US troops at an airbase].

"If the US insults the prophet, their sons and soldiers are in Afghanistan, and the people of Afghanistan always show that they are very sensitive about their religion."

News usually travels slowly in a country where most people are illiterate and an electricity supply is an elite privilege. Protests are most likely to erupt after Friday prayers when preachers might discuss the film.

Afghanistan has endured deadly riots several times in recent years in response to western actions viewed as insulting to Islam.